The present invention generally relates to an electric switch and, more particularly, to a high precision, compact contact switch.
Hitherto, contact switches generally used for detecting the position of an object have utilized either a reversing mechanism and leaf contacts. Since these prior art contact switches make use of a leaf spring, they have a problem in that change in operating position of the contact arrangement is apt to occur frequently.
In view of the foregoing, a high precision compact switch capable of exhibiting a precision in the order of microns has been proposed such as disclosed in Japanese Utility Model Application No. 58-127136 filed in Japan in the name of the same assignee of the present invention. The switch disclosed therein is of a construction wherein a contact element made of a rod is structured to provide a cross-bar design and wherein a movable contact element in the form of a rod provided in a plunger is urged by a return spring to constantly contact a pair of fixed contact elements each in the form of a rod secured rigidly to a casing.
It has, however, been found that, in the switch disclosed in the above mentioned application, since the pair of the fixed contact elements are securely fitted into respective apertures in the casing independently of each other in separated form, they cannot always be fabricated accurately in parallel relation to each other or in perpendicular relation to the direction of movement of the movable contact element. In view of this, it is difficult to guarantee the high precision in the order of submicrons, that is, 1 .mu.m or smaller.